Speaking of map issues seen in the stream, I figured out what was going on with the button. I used the same exact setup as the official maps at first, but when I was testing the map, I noticed that the func_door_rotating that's used as the interactable entity was solid to players, despite the "Non-solid to players" flag being enabled. I think that and the "Passable" flag are swapped somewhere, since "Non-solid to players" makes it non-solid to physics objects and "Passable" makes it non-solid to players.
Anyway, since players can't collide with the entity, it's possible for them to get very close to the button. If they're inside the func_door_rotating and looking at a downward angle, they can't use the button. The only way to fix this was to make the func_door_rotating smaller so that the player isn't standing inside the button when they're close to it.
I checked in the official maps, and all buttons are like how the button in my map originally was: an invisible box around the button that the player collides with.